In a conventional grinding machine for plate glass, when the periphery edge of plate glass is to be chamfered or ground round, a grinding wheel for chamfering is prepared and used for chamfering purposes, or a grinding wheel for forming a round edge is prepared and used for rounding purposes.
When a plate glass like a car pane is ground round in a part of the periphery edge thereof, and is chamfered in the other part of the periphery edge thereof, for example, a specified part of the periphery edge is firstly ground by a grinding wheel for forming a round edge, and then the remaining part of the periphery edge is ground by a chamfering wheel replacing the grinding one. However, such a means is very inefficient in working because it will take time to replace the grinding wheel and the grinding program must be run twice.
In view of the above, it is an object of the present invention to provide a numerically controlled grinding machine for plate glass which is capable of forming a round edge and a chamfered edge on required parts of plate glass by running the grinding program once without replacing the wheel.